Two-cycle internal-combustion engine



Oct. 21 1924.

W. J. STILL Two-CYCLE INTERNAL COMBUSTION,ENGINE n Filed July 2a'. 1920y Sheets-Shes?. 1

M M NW 1 N@ Q d w A u Q m. Q. k E E N QQ b h.. i m.

W. J. STILL TWQCYCLE INTERNAL COMBUSTION ENGINE Filed July 28, 1920 2 Sheets-snee'. 2

Patented ct. 21, 1924.

' WILLIAM rosErH STILL, or Wnsrivrrnsrnn, Lennon, ENGLAND.

TWO-CYCLE INTERNAL-COMBUSTION ENGINE.

Application led J'111y`28, 1920. Serial No. 339,582.

(GRANTED UNDER THE PROVISIONS F THE ACT 0F MARGH 3, 1921, 41 STAT. L., 1313.)

i" 0 all 'whom t may concern:

Be it known that I, VILLLAM JosErH STILL, a subject of the King of Great Britain, and resident of Westminster, London, England, have invented certain new and useful improvements Connected with Two- Cycle internal-Combustion Engines (for Which-1 have iiled application in Great Britain, No. 14,456, dated June 6, .1919), of which the following is a specification.

This invention relates to; improvements connected with two cycle internal combustion engines and has reference to internal combustion engines of that type where steam is 'used expansively at the backs of the combustion engine pistons to assist the combustion cycle.

Intwo cycle internal combustion engines it has been suggested to utilize the scavenge pump as a motor for starting up purposes compressed air being usually employed as the motive iuid although it has been realized that steam or other elastic fluid would equally well serve the purpose.

The present invention has for its object the provision of means for enabling the scavengepump -to be conveniently used for the purpose of starting up under steam,

. engines of the type Ito which my invention relates when the main cranks are at dead centre and also to be used for assisting the main cylinders in overcoming the inertia of the load and the primary feature of the invention is the provision of valve arrangements in connection with the scavenge pump Whereb;7 the admission of steam to the scavenge pump by way of al hand operated control valve causes the scavenge pump to ad- `inst itself automatically to operate as a motor, while immediately the steam supply is cut oif from the pump the latter again operates in its normal way.

In the accompanying drawings, I have illustrated my invention, Fig. 1 being a sectional view of a double acting scavenge pump cylinder adapted to operate in accordance with my invention and Fig'. 2 is a sectional View of a control valve for controlling the steam from a boiler 31 admission, while Fig. 3 is a sectional view of an auxiliary starting valve for application to the combustion engin-e cylinders in cases where big starting efforts are required, this valve also serving as a relief valve. Fig.

4 is a diagram illustrating a complete prime mover set according to one embodiment of this invention.

Referring to Figs. 1 and 2 and 4 of the drawings and assuming the invention to be applied to a two cycle internal combustion engine which it is desired should be capable of starting up from any position of crank 1 propose to connect the engine scavenge pump piston 1 to the main crank shaft 29 of the engine at a suitable crank angle by means` of a. connecting rod 32 of suioient strength to transmit the starting effort. This Vpump piston 1 operates in the cylinder 2, the ports 3 and 4 of which are controlled by a piston valve 5. The numeral 6 designates the suction port of the pumpfwhiehy is provided with a valve 7 and `air entering through .this suction valve during the normal Voperation of the pump enters the valve chest 8 through the slots 9, and by reason of the operation of the piston valve 5 the scavenging air will be delivered under pressure alternately through the ports 3 and 4 to the two delivery outlets 10 and 11 and from thence to the cylinders (through the pipes 34. f A. draftV takes place through the outlet 43. The valve 7 is controlledby the spring 12 and during normal operations is maintained in open position, the spring 12'rfaising the sliding sleeve 13 which in turnraises the valve 7 by engaging the collar 14 upon ythe upper end ofthe valve stem. The sliding sleeve 13 has a port 15 and the operation of the device as a whole is as follows As ybefore indicated during normal operation the valve VFis opened and the pump operates in the usual way to scavenge the cylindersBO of the internal combustionengine. If,.however,`the main crank 29 of vthe engine is at dead centre as shown inFig.

4 and the engine cannot be started'under steam in the ordinary way, the steamis aflmitted through the port'lt into the chamber 17 above the valve 7 and sliding sleeve 13. This steam acts upon the upper enelv of the stem of the valve 7 and the sleeve 13 and the valve vstem 7 which together constitute a piston of the area of the sleeve 13 move down together under the steam pressure i until the valve 7 seats itself. The sleeve 13 whichwill not have been depressed sufficiently to open the port 15 then continues to move until it reaches its lowest 'position as'shown in the drawings when steam passes through the port 15 to the valve ch-est 8 through the slots 9 and thence through one or other of the ports 3 or af to operate the piston 1 of the pump and thus start the engine. The pump operates as a steam engin-e having a cut 0E of about 90 per centum and exhausts to the main engine cylinders and it will be understood that it is only necessary to supply steam to it :fork a very short period, i. e., just long enough to cause the engine crank to move from dead centre position. For this reason l propose to provide a control valve for controlling the admission of steam to the port 16 of the form shown in Fig. 2 although it will be understood that other Jforms of control valve may be employed. This special steam control valve consists of a valve 18. normally held closed by a spring 18a its stem 19k being engaged by a pivoted hand lever 20 which when depressed opens the valveV to admit steam to the port 16. Tn starting up an engine constructed in accord ance with my invention, the operator will lirst open the ordinary main stop valve 37 to pass steam by way o1 the pipe 38 to the steam ends of the cylinders through suitableinlet and exhaust valves 35. The valves 'are operated by cams 35 on a shaft 35b which shaft is connected tothe driving shaft by gears 101, 102 and an internal shaft 103V as indicatedv in the Figure 4. Tf the engineY main cranks are in any but dead cen tre position the engine will start and it will be unnecessary to employ the above described gear. If,'however, the engine main cranks are in such a'position that it cannot start, the operator depresses the lever 2O and steam then passes by way of the ports 21 and 22 to the port 16 and the engine can be started' up by the operation of the scavenge pump as, steam engine in the manner before described. The pump will operate as a steam 'engine as long as the operator keeps the lever 20,-depressedV but the pump is not intended for continuous use, and the lever 20 should be released as soon as the engine cranks have moved to a starting position where steam can pass to the backs of the combustion engine cylinders through suitable valves 35. lt will 'be understood that immediately the lever 20 is released, the pump commences to operate in the normal way as a scavenge pump to supply scavenging air to the cylinders 30 by way of pipes 39 and inlet ports 40. Although the scavenge pump is only intended for use as an initial starting device, its operation as a steam cylinder may be pro longed sullicently to overcome the inertia of the load. This may be necessary in instances 'for traction purposes but normal operation shouldY be re-established as soon as suiicent speed has been attained to allow normal functioning to be resumed.

1n cases where great starting efforts are required, however, as for instance where the engines are employed for" driving locomotives, an auxiliary starting valve of the form shown in Fig. 3 may be employed so as to obtain the principal starting effort from the main engine cylinder. The valve proper 23 is in etlect a relief valve normally closing the port 24- of the combustion chamber of the' engine cylinder. It is loaded by the spring 25 with suiiicient pressure towithstand the normal maximum combustion pressure but to lii't it some predetermined abnormal pressure is reached when the pres'- sure will at once be relievedv through the port 26.

For starting purposes this valve 23 will be li'lted from its seat by introducing steam under the piston 27 by wayo the pipe 41 and sepa-rate valve 18. through the port-28. This act-ion alone will assist in starting by releasing compression from the combustion chamberand thus relieving the main engine pistons of the negative work oi! compression. Tf, however, theport 26 is comiecte'dto a steam supply pipe such as 42 'fitted 'with a control valve 18, When the Valve 23`is lifted steam can be admitted to Yand 4exhai'ist'ed from the combustion side of the main pis'- ton in the same manner as it is 'admitted to and exhausted Jfrom the other side, and the engine will thus become a double` acting steam engine. This valve 104 is shown in Figure el as a. two Way valve, the normal position of which is indicated by dotted lines. Tn this normal position the outlet 26 iss in Vdirect communication with the 'atmospherel while in the other position the valve and Youtlet is in connection with the steam supply by way of thepipe 4:2. The supply of steam tol the port 26 can be controlled by' a start-ing valve vo1 the form shown in Fig. 2,' a single one of these valves :serving to control'sim'ultaneously the supply of. steambotht'o the scavenge pump and. the 'working 'cylinder devicesl as: shown in Fig. a.' separate Valve however, will be desirable to control the steam4 admission to the4 port 2S-"or, other arrangements made to ensure the. valve 23 being liftedv prior to the passage ofsteam to the port 26. 'Y

The main cylinders 30 must be heated to a temperature above 212.o F. before starting as otherwise steam condensation will occur` within the main cylinders and may cause diiitlculty in starting up the combustion side of the engine when' normal running conditions are established.' This presentsno dit-` i'iculties in engines constructed in accordance with my prior British Letters Patent Nos. 17,717 of 1912 and. 25,356 vof1910,'vvhere the cylinder ackets form part orq the steam generation system, or steam is 'introduced into the jackets, respectively.

The temperature `inai1itained should be well'above 2120 in fact, because it is ad? lll) soon be obtained to permit combustion to be easily and safely commenced.

Water relief valves of ample size should be provided on the scavenge cylinder heads and these may be set to such a pressure as to serve as pressure relief valves also,l the pressure they are set to being determined by the starting effort required.

l claiml. A prime mover co-mp-rising an, internal combustion engine cylinder, a. scavenge pump operating on the same crank shaft as the internal combustion engine cylinder but at a different angle, a boiler for the production of steam under pressure, means for admitting steam from the boiler tothe scavenge pump, and valve means associated with said scavenge pump adapted to permit said scavenge pump to function auto-matically asI a steam cylinder when starting the engine and as an air pump for supplying scavenging air to the internal combustion engine cylinder when the steam supply to the scavenge pump is cut off.

2. A prime mover comprising an internal combustion engine cylinder adapted to operate partially under steam,. a scavenge pump operating on the same crank shaft as the internal combustion engine cylinder but at a different angle, a boiler for the production of steam under pressure, means for admitting steam from the boiler to the scavenge. pump, means for also admitting steaml from the bo-iler to the steam side of the internal combustion engine and valve means associated with said scavenge pump adapted to permit said scavenge pump to function automatically as a steam cylinder when starting the engine and as an air pump for supplying scavenging air to the internal combustion engine cylinder when the steam supply to the scavenge pump is cut off.

3. A prime mover comprising an internal combustion engine cylinder adapted to operate partially under steam, a scavenge pump operating on the same crank shaft as the internal combustion engine cylinder but at a different angle, a boiler for the production of steam under pressure, means for admitting steam from the boiler to the scavenge pump forthe purpose of starting the internal combustion engine comprising a valve whereby said scavenge pump is adapted to operate on occasion as a steam cylinder and for supplying scavenging air to the internal combustion engine, and a further-l valve adapted to be operated automatically by the steam pressure tofirst close said suction port and then admit steam to said scavenge pump, and means for controlling the admission of steam from the boiler to the steam side of the internal combustion engine cylinder. Y

4. A prime mover comprising an internal combustion engine cylinder adaptedtooper'- ate partially under steam, a scavenge pump' operating on the same crank shaft as the internal combustion engine cylinder but at a different angle, a boiler for tliefproduction of steam under pressure, means for admitting steam from the boiler to the scavenge pump, means for also admitting steam from the boiler to the steam side of the internal l combustion engine, and valve means asso'- ciated with said scavenge pump adapted to permit said scavenge pump to function automatically as a steam cylinder and as an air pump for supplying scavenging air to the internal combustion engine cylinder when the steam supply to the scavenge pump is cut off and further valve means for admitting steam to the internal combustion side of the internal combustion engine cylinder to assist in starting the same by enabling such internal combustion engine cylinder to operate as a double acting steam engine.

5. A prime mover comprising an internal combustion engine cylinder, a scavenge pump operating on the same crank shaft as the internal combustion engine cylinder but at a different angle, a boiler for the production of steam under pressure, means for admitting steam from the boiler to the scavenge pump comprising a double piston valve, controlling ports at both ends of the scavenge pump7 inlet ports intermediate the ends of said double piston valve, an automatic valve controlling said inlet ports and an air inlet port, a hand operated valve controlling the supply" of steam to said automatic valve, said automatic valve being adapted to operate, under the steam pressure, to close the air inlet port and admit steam through the inlet ports from whence it is admitted to each end of the scavenge pump alternately by the double piston valve, said automatic valve being adapted. to automatically place the air inlet port into communication with the inlet ports when the steam supply is shut ofi" whereby said scavenge pump is adapted to function as an air pump and to supply air to the internal combustion engine cylinder for scavenging purposes.

6. A prime mover comprising an internal combustion engine cylinder, a scavenge pump operating on the same crank shaft as the internal combustion engine cylinder but at a different angle, a boiler for the production of steam under pressure, means for admitting steam from the boiler to the scavenge pump comprising a double piston valve controlling ports at both ends of the scavenge pump7 inlet ports intermediate the ends of said double piston valve, an automatic valve controlling said inlet ports and an air inlet port comprising a valve seating' on said air inlet port, a stem projecting from said valve having a sleeve slidably mounted thereon7 a casing enclosing said valve and sleeve, a partition dividing said casing into two compartments, a steam admission port communicating with one of said compartments a transfer port in said sleeve adapted to place the two compartments into `Communication with each other when the valve is on its seating and the air inlet port Closed7 a spring engaging said sleeve and normally tending to hold said sleeverin a position where communication between the compartments is broken and the valve off its seat, a hand operated valve controlling the admis- Sion of steam to one of said compartments through the port provided, said steam serving to move the sleeve against the pressure of the spring so as to cause the transfer port to bridge the partition separating the Compartments and to thereby force the valve on to its seating so as to close the air inlet port, thespring serving to return the sleeve to its normal position and the air inlet port to open when the steam supply is shut oli1 whereby the scavenge pump is adapted to function as an air pump and to supply air to the internal combustion engine cylinder for scavenging purposes.

ln testimony whereof, I aiiiX my signature.

WLLIAM JOSEPH STILL. 

